1. Field of the Invention
The present invention relates to semi-automatic and fully automatic building intercom systems.
2. Description of the Related Art
It has been an increasing concern by apartment builders to provide an apartment intercom/door release system that not only is secure, but also reliable. As apartment buildings with 200 apartments or more become commonplace, it is extremely burdensome and time consuming to trace every wire in an intercom system to locate a fault. In addition, the entire intercom system may be out of order until the fault is found.
The related art is represented by the following patents of interest.
U.S. Design Pat. No. 394,653, issued on May 26, 1998 to Tetuaki Kato et al., shows an ornamental design for an intercom sub-station. Kato et al. do not suggest an automatic intercom system according to the claimed invention.
U.S. Pat. No. 3,484,561, issued on Dec. 16, 1969 to John T. Matthews, describes a combination telephone-intercom and door release system. Matthews does not suggest an automatic intercom system according to the claimed invention.
U.S. Pat. No. 3,532,820, issued on Oct. 6, 1970 to Norbert Holm, describes an intercom system employing a matrix system having a telephone at each junction that allows a visitor to select and call a suite, carry on a two-way private conversation with the tenant, and that allows the tenant to activate a remote door release. Holm does not suggest an automatic intercom system according to the claimed invention.
U.S. Pat. No. 3,665,116, issued on May 23, 1972 to Allan Holstrom, describes an intercom system which requires only two wires to transmit signals between a speaker-microphone unit located at a central or foyer station, and any one of a plurality of such units located at apartments remote from the foyer station, as well as to transmit a door unlatching signal from any remote unit to a release mechanism at the foyer station. Holstrom does not suggest an automatic intercom system according to the claimed invention.
U.S. Pat. No. 4,188,511, issued on Feb. 12, 1980 to Maurice I. Smith et al., describes a multi-link telephone intercom system including a separate link selector for each link and a separate link scanner for each subscriber station. Smith et al. do not suggest an automatic intercom system according to the claimed invention.
U.S. Pat. No. 4,196,317, issued on Apr. 1, 1980 to Everhard H. B. Bartelink, describes a telephone intercom system which provides combined telephone and intercommunication services to telephone subscribers with multiple subscriber sets. Bartelink does not suggest an automatic intercom system according to the claimed invention.
U.S. Pat. No. 5,568,542, issued on Oct. 22, 1996 to Max Borshchevsky et al., describes a self-correcting intercom system with circuitry to detect faults within the circuitry and reset the system to a pre-fault condition on the occurrence of a fault. Borshchevsky et al. do not suggest an automatic intercom system according to the claimed invention.
None of the above inventions and patents, taken either singularly or in combination, is seen to describe the instant invention as claimed.